German Patent DE-OS No. 29 07 349 relates to the manufacture of pharmaceutical compositions with cytostatic properties, and which contain as the pharmacologically active ingredient triglycidylisocyanurate (TGI). European Pat. No. 0 033 503 discloses compounds useful in the manufacture of pharmaceutical compositions having cytostatic properties. Such compositions contain N-heterocyclic compounds having at least 2 glycidyl substituted ring nitrogen atoms in amide and/or imide form. In fact, this European patent discloses a multitude of special classes of compounds of the above mentioned type, all of which can be used for the manufacture of pharmaceutical compounds that exhibit tumor inhibiting properties.